Employing the technique of quantitative constant pressure aqueous perfusion, we are studying the effects of various factors on facility of aqueous outflow and their possible interrelationships, particularly, the intraocular pressure and tension on the iridocorneal angle as produced by cyclotonia. In perfusions of excised eyes, the effect of cyclotonia on facility of aqueous outflow is simulated by the technique of lens depression. We are likewise attempting to obtain new information regarding the structural basis for changes in facility of outflow produced by the above mentioned factors by fixing eyes at various intraocular pressures with varying tension on the iridocorneal angle by buffered glutaraldehyde infusion. These eyes will be examined by thin section light microscopy, transmission and scanning electron microscopy. In a second set of experiments, eyes freshly enucleated from fetal stumptailed Macaques and fetal and newborn dogs will be perfused by quantitative constant pressure aqueous perfusion and fixed by infusion of buffered glutaraldehyde into the anterior chamber at physiologic pressure. Segments of iridocorneal angle and related structures will be examined by transmission and scanning electron microscopy. In a third set of experiments, freshly enucleated canine and other subprimate vertebrate eyes are being studied by constant pressure quantitative aqueous perfusion in order to examine the factors which affect the facility of outflow in these species. The factors under current investigation include the intraocular pressure, hyaluronidase sensitivity, rapid aqueous flow ("washout") and aqueous constituents. BIBLIOGRPAHIC REFERENCES: Van Buskirk, E.M.: Changes in the facility of aqueous outflow induced by lens depression and intraocular pressure in excised human eyes, Amer. J. Ophthal., 82: 736-740, 1976. Van Buskirk, E.M.: Trabeculotomy in the immature, enucleated, human eye. Invest. Ophthal., 16:63-66, 1977.